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Ionic liquid pretreatment of cellulosic biomass: Enzymatic hydrolysis and ionic liquid recycle
Author(s) -
Shill Kierston,
Padmanabhan Sasisanker,
Xin Qin,
Prausnitz John M.,
Clark Douglas S.,
Blanch Harvey W.
Publication year - 2011
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.23014
Subject(s) - cellulose , ionic liquid , chemistry , hydrolysis , cellulosic ethanol , biomass (ecology) , enzymatic hydrolysis , aqueous solution , solvent , salt (chemistry) , aqueous two phase system , raw material , cellulase , lignocellulosic biomass , chromatography , organic chemistry , chemical engineering , catalysis , oceanography , engineering , geology
Ionic liquids (ILs) are promising solvents for the pretreatment of biomass as certain ILs are able to completely solubilize lignocellulose. The cellulose can readily be precipitated with an anti‐solvent for further hydrolysis to glucose, but the anti‐solvent must be removed for the IL to be recovered and recycled. We describe the use of aqueous kosmotropic salt solutions to form a three‐phase system that precipitates the biomass, forming IL‐rich and salt‐rich phases. The phase behavior of [Emim][Ac] and aqueous phosphate salt systems is presented, together with a process for recycling the [Emim][Ac] and enzymatically hydrolyzing the cellulose. This process reduces the amount of water to be evaporated from recycled IL, permitting efficient recycle of the IL. Material balances on the process, with multiple recycles of the [Emim][Ac], quantify the major components from a Miscanthus feedstock through the pretreatment, separation, and enzymatic hydrolysis steps. A more rapid and higher yielding conversion of cellulose to glucose is obtained by use of the three‐phase system as compared to the cellulose obtained from biomass pretreated with IL and precipitated with water. The addition of a kosmotropic salt during the precipitation results in partial delignification of the biomass, which makes the substrate more accessible, enhancing the enzymatic hydrolysis. Biotechnol. Bioeng. 2011; 108:511–520. © 2010 Wiley Periodicals, Inc.